The overall objective of this proposal is to determine the role(s) of specific growth regulatory pathways in the pathogenesis of human prostatic cancer. Expression of selected growth factor genes and protooncogenes during natural disease progression will be evaluated in surgically-excised specimens from patients. Gene expression which correlates with one or more aspects of the pathobiology of human prostate cancer will be examined further in a well characterized experimental model of human prostatic tumor growth and metastasis in athymic nude mice. Expression of the following growth factors or growth factor receptor genes will be examined in terms of both specific RNA (via Northern analysis), gene amplification (Southern analysis), and protein product (immunohistochemistry and Western analysis), where feasible: (1) transforming growth factor alpha (TGF-alpha) and its receptor, (2) the epidermal growth factor receptor (EGFr), (3) c-erbB-2, a gene coding for a modified EGF receptor, and (4) transforming growth factor beta (TGF-beta1). A combination of immunohistochemical staining with the appropriate antibody and Western blotting will be used (1) to relate RNA levels to protein product expression and (2) to permit identification of the cell type synthesizing the protein of interest. Correlative expression of these genes will be related to function by analysis of the role(s) of these gene products in the growth and/or metastasis of variants of the human prostate carcinoma cell line PC-3 and DU145 in athymic nude mice. This will be accompanied by (1) measurement of specific gene expression in existing PC-3 and DU145 variants and (2) selection of PC-3 variants which exhibit high or low expression of these genes followed by subsequent evaluation in nude mice. Where possible, confirmation of putative functional involvement of these genes will be sought by genetic modification of phenotypic variants via transfection with the appropriate gene(s). These studies will permit identification of the role(s) of these growth factor and growth factor receptor genes in the natural progression of human prostatic cancer. Equally significant, these experiments will permit experimental evaluation of the relation between expression of these genes and the pathobiological phenotype of this common human tumor.